The present invention relates to methods and systems for manufacturing fiber insulation, and more particularly to methods and systems for manufacturing wool fiber insulation via a gas attenuation process.
One prior art system for manufacturing glass wool insulation is described in U.S. Pat. No. 4,090,241 to Houston, entitled xe2x80x9cMethod for Estimating and Controlling the Mass Flow Rate of a Free Falling Fluid Stream,xe2x80x9d issued May 16, 1978, the entirety of which is hereby incorporated by reference herein. In the system described in Houston, raw material or batch is conveyed from storage bins to a melting furnace to form molten glass. The molten glass free falls through several spaced bushings, each of which is positioned above a respective fiberizing apparatus. The fiberizing apparatus includes a centrifuge device that projects radial streams of molten glass into a transverse gaseous blast directed downward toward a horizontally moving collecting belt or forming chain. The gaseous blasts form the molten streams of glass emanating from the centrifuge into hollow cylindrical fiber veils that are deposited upon the forming chain. Before reaching the forming chain, it is common to treat the flowing fibers with a binding material. An uncured glass wool pack is thereby built upon the forming chain including glass fibers,coated with binding material. The wool pack then passes through a thermal oven wherein the binder cures. The final wool pack is then typically chopped into bans of a desired length and packaged. These systems are often referred to as gas attenuated fiber insulation manufacturing systems. The products formed thereby are referred to as gas attenuated fiber insulation products.
In some commercial embodiments of a manufacturing system described above, a forming bucket is positioned between each centrifuge and the collecting belt or forming chain. The hollow cylindrical glass fiber veils, which include millions of glass fibers, are projected downward towards the chain or belt through the forming buckets. The veils are then treated with binder and collected on the forming chain or collecting belt. Each forming bucket oscillates or swings perpendicularly to the length and direction of the forming chain or collecting belt. The plurality of forming buckets thereby cooperate to direct the fiber veils to deposit the fibers evenly across the forming chain.
A portion of this system is illustrated in FIG. 1. A bucket 10, which is shown in cross section, swings perpendicularly to the length and direction of the forming chain or collecting belt 12, which moves in the direction indicated by the arrows. The bucket 10 is made to swing by partially rotating arms 16 back and forth to direct the glass fibers 14 (moving in the direction indicated by the double arrows) through bucket 10 and evenly across the width of the belt 12 as it moves.
FIGS. 2A and 2B illustrate forming buckets currently in use in a manufacturing system described above. FIG. 2B is a side elevational view of a bucket 40 used with an 800 mm diameter fiberizer. Buckets used in connection with an 800 mm diameter fiberizer are sometimes referred to herein as xe2x80x9c800 mm bucketsxe2x80x9d. The bucket 40 has a top or input diameter DI of approximately 3xe2x80x2-6{fraction (13/16)}xe2x80x3 and an output diameter DO of 2xe2x80x2-6xc2xcxe2x80x3. The bucket 40 has a height H1 of 7xe2x85x9exe2x80x3 and a height H2 of 2xe2x80x2-9xc2xdxe2x80x3. FIG. 2A is a side elevational view of a bucket 50 used in connection with a 600 mm diameter fiberizer. Buckets of this type are sometimes referred to herein as xe2x80x9c600 mm bucketsxe2x80x9d. The bucket 50 has a top or input diameter DI of approximately 2xe2x80x2-7xc2xdxe2x80x3 and an output diameter DO of 1xe2x80x2-10{fraction (11/16)}xe2x80x3. The bucket 40 has a height H1 of 1xe2x80x2-1{fraction (9/16)}xe2x80x2 and a height H2 of 2xe2x80x2-7⅝xe2x80x3.
As can be seen in FIGS. 2A-2B, both prior art buckets 50, 40 consist of a hollow, linear conical portion that terminates at a circular sleeve portion having a consistent diameter. These buckets are typically welded at their inlets to a mounting collar, not shown, that includes the arms 16 that are rotated to swing the buckets, as described above with respect to FIG. 1, across the forming chain or collecting belt.
As buckets 40, 50 swing during the gas attenuation process, some of the fibers that flow through the buckets contact the inner walls of the buckets, primarily due to turbulence in the fiber stream within the forming buckets. The fibers that collide with the inner surface of a bucket tend to entangle and form what are referred to in the industry as xe2x80x9cropes.xe2x80x9d The binder that is sprayed into the fiber stream as it exits the forming buckets cannot fully penetrate these ropes, leading to poor binder distribution and poor mass density of the resultant wool fiber insulation mats and affecting both the physical and mechanical properties of the insulation mats.
Therefore, there is a need to reduce or eliminate the formation of fiber ropes in a gas attenuated fiber insulation manufacturing process. To that end, there is a need for a new forming bucket that reduces or prevents the formation of fiber ropes in insulation mats, particularly in gas attenuated fiberglass insulation mats.
A forming bucket for use in the preparation of gas attenuated fiber insulation products is provided. The forming bucket includes a tubular member having a fiber inlet and a fiber outlet. The tubular member has a conical portion disposed between the fiber inlet and the fiber outlet. The conical portion has a smooth curvilinear surface for minimizing turbulence in a fiber stream flowing through the forming bucket during the gas attenuation process.
The forming bucket so provided is more aerodynamic than prior art buckets and reduces collisions between the fibers of the fiber stream and the interior surface of the forming bucket. This, in turn, reduces the formation of fiber ropes that are difficult to impregnate with binder. Binder distribution thereby improves along with the mass density of the fiber mat, resulting in improved physical and mechanical properties of the fabricated insulation products.
The above and other features of the present invention will be better understood from the following detailed description of the preferred embodiments of the invention that is provided in connection with the accompanying drawings.